The present invention relates generally to systems for effecting flow of bulk particulate material, and more particularly to an improved arrangement for maintaining efficient flow of bulk particulate material through a curved section of a duct or chute in a manner to prevent clogging.
A problem sometimes encountered in systems for conveying bulk particulate material through flow ducts or conduits having a curved section is that clogging may occur in the curved section due to the fact that a substantially zero velocity layer is formed over the internal duct surface of greatest radius. As a consequence, as particulate material, such as air entrained particulate material, passes through the curved duct section and impacts the internal concave curved surface, it tends to stagnate and may cause significant clogging which impedes flow through the duct. This problem is frequently encountered with commercial type grass mowers and the like which employ one or more rotary cutter blades and an associated shroud operative to both cut the underlying grass and effect air entrained passage of the cuttings to a chute or duct through which the cuttings pass to a receptacle. The chute or duct generally includes at least one curved section through which the clippings pass to an upstanding passage of sufficient height to drop the cuttings into the receptacle. As the air entrained grass clippings pass through the curved chute section and impact the internal concave surface over which the zero velocity layer is formed, the clippings tend to stagnate and cause clogging which impedes flow through the chute. This problem is particularly acute with damp or wet grass, and often requires interruption of mowing to clear the clogged chute or duct. The adverse effects of such clogging are thus readily apparent.